1. Field of the Invention
This invention relates to the field of protocol analyzers. In particular, it relates to triggering mechanisms in protocol analyzers.
2. Description of the Related Art
Protocol analyzers are used for monitoring, analyzing and testing high-speed serial storage area networks (SANs) and sub-systems. The systems that are analyzed may, for example, use high-speed serial protocols such as Fibre Channel, Ethernet, and Serial Attached Small Computer System Interface/Serial Advanced Technology Attachment (SAS/SATA) protocols.
Protocol analyzers resolve events that cause performance problems into human readable form and enable users to design, implement, test, and evaluate SANs and their components. As the systems being analyzed use high-speed interfaces, limited buffers are available to capture events of interest. Therefore, the analyzer must be programmed to be a triggered to record specific events.
A trace tool application of an analyzer is used to define specific conditions under which a capture of events triggers and stops. The trace tool provides a traffic library with pre-defined and user-defined templates for frames, ordered sets, and errors which can be used for triggers. For example, a trace control can be configured to wait for a specific network traffic condition to occur, such as a certain frame type, before beginning a capture.
If there is a sequence of events that can be predicted easily, or if patterns are repeatable and unique to a failure mode, it is straightforward to trigger the trace at the required event. However, there are instances where the trace needs to be triggered when there is a lack of an event. This may happen when an event should have occurred but did not, or if a different event occurred in its place.